- Maintained strong balance sheet with $213.2 million in cash, cash
equivalents and investments to fund projected operating requirements
into the second half of 2019 -

May 08, 2017 07:00 AM Eastern Daylight Time

CAMBRIDGE, Mass.--(BUSINESS WIRE)--Acceleron Pharma Inc. (NASDAQ:XLRN), a clinical stage biopharmaceutical
company focused on the discovery, development and commercialization of
innovative therapeutics to treat serious and rare diseases, today
provided a corporate update and reported financial results for the first
quarter ended March 31, 2017.

“In the first quarter, we made significant progress across our entire
pipeline. Our luspatercept program in MDS and beta-thalassemia continues
to build momentum, as we look to complete enrollment of the MEDALIST and
BELIEVE Phase 3 studies ahead of schedule, and expand into additional
patient populations where there are limited treatment options, including
first-line, lower-risk MDS and myelofibrosis,” said Habib Dable,
President and Chief Executive Officer of Acceleron. "As we continue to
explore further expansion opportunities for luspatercept, we are also
preparing to expand our wholly-owned pipeline into a second
neuromuscular disease, with the expected initiation by mid-year of a
Phase 2 study with ACE-083 in patients with Charcot-Marie-Tooth disease.”

DEVELOPMENT PROGRAM HIGHLIGHTS

Hematology

Luspatercept in myelodysplastic syndromes (MDS)

Luspatercept is being developed to treat anemia and reduce or
eliminate the need for red blood cell transfusions in patients with MDS,
a rare disorder in which bone marrow fails to produce enough healthy
blood cells.Luspatercept is being developed as part of the
global collaboration between Acceleron and Celgene.

Enrollment in the MEDALIST Phase 3 clinical trial is expected to
complete in the second quarter of this year. The MEDALIST Phase 3
study is enrolling 210 patients to evaluate the efficacy and safety of
luspatercept in patients with anemia due to lower-risk MDS with ring
sideroblasts who require red blood cell (RBC) transfusions.

Acceleron and Celgene announced plans to initiate a third Phase 3
trial with luspatercept in early 2018. The new Phase 3 trial will
evaluate luspatercept treatment versus standard-of-care in the
first-line treatment setting for lower-risk MDS patients.

Luspatercept in beta-thalassemia

Luspatercept is designed to treat severe, chronic anemia and reduce
RBC transfusion-dependence in adults with beta-thalassemia, a rare
genetic disorder that reduces the production of hemoglobin. Luspatercept
is being developed as part of the global collaboration between Acceleron
and Celgene.

Enrollment in the BELIEVE Phase 3 trial is expected to complete in
the second quarter of this year. The BELIEVE Phase 3 study is
enrolling 300 patients to evaluate the efficacy and safety of
luspatercept in patients with anemia due to beta-thalassemia who
require regular RBC transfusions.

ACE-083 is designed to increase muscle mass and strength in target
muscles for diseases that cause debilitating focal muscle loss.

Enrollment and treatment are ongoing in Part 1 of the ACE-083 Phase
2 study in patients with FSHD, one of the most prevalent forms of
muscular dystrophy.

Announced plans to initiate a second Phase 2 clinical trial with
ACE-083 in patients with Charcot-Marie-Tooth (CMT) disease, one of
the most common inherited neurologic diseases leading to focal muscle
weakness, by mid-2017.

Preclinical Research

Acceleron continues its research on several molecules targeting
musculoskeletal diseases, fibrotic disorders and other serious diseases.

The Company plans to initiate a Phase 1 healthy volunteer clinical
trial this year with ACE-2494.

Host a Research and Development Day to discuss preclinical research
and clinical development activities in 2H 2017

Financial Results

Cash position – Cash, cash equivalents and investments as of
March 31, 2017 were $213.2 million. As of December 31, 2016 the
Company had cash, cash equivalents and investments of $234.4 million.
We believe that existing cash, cash equivalents and investments will
be sufficient to fund projected operating requirements into the second
half of 2019.

Revenue – Collaboration revenue for the first quarter was $3.7
million. The revenue is all from our Celgene partnership and is
primarily due to cost sharing revenue of $3.6 million related to
expenses incurred by the Company in support of our partnered programs.

Costs and expenses – Total costs and expenses for the
first quarter were $29.6 million. This includes R&D expenses of $21.7
million and G&A expenses of $7.8 million.

Other income, net – Other income, net for the first quarter was
$0.5 million primarily due to interest income.

Net loss – The Company's net loss for the first quarter
ended March 31, 2017 was $25.4 million.

Conference Call and Webcast

The Company will host a live conference call and webcast to discuss its
first quarter 2017 financial results and provide a corporate update on
May 8, 2017, at 8:00 a.m. EDT. Participants can access the live
conference call by dialing 877-312-5848 (domestic) or 253-237-1155
(international) and refer to the “Acceleron Earnings Call.”

A replay of the webcast will be available approximately two hours after
the event on the Company's website.

About Acceleron

Acceleron is a clinical stage biopharmaceutical company focused on the
discovery, development and commercialization of innovative therapeutics
to treat serious and rare diseases. Its pioneering research platform
leverages the powerful biology behind the body’s ability to rebuild and
repair its own cells and tissues. This approach to drug discovery has
generated four therapeutic candidates that are currently in clinical
trials. The Company’s lead therapeutic candidate, luspatercept, is being
evaluated in Phase 3 studies for the treatment of the hematologic
diseases myelodysplastic syndromes and beta-thalassemia under a global
partnership with Celgene Corp. Acceleron is also advancing clinical
programs in the fields of oncology and neuromuscular diseases and has a
comprehensive preclinical research effort targeting fibrotic and other
serious diseases.

Net unrealized holding gains on short-term and long-term investments
during the period

25

245

Comprehensive (loss) income

$

(25,382

)

$

5,306

Net (loss) income per share applicable to common stockholders:

Basic

$

(0.66

)

$

0.14

Diluted

$

(0.66

)

$

0.13

Weighted-average number of common shares used in computing net
(loss) income per share applicable to common stockholders

Basic

38,404

36,911

Diluted

38,404

38,666

Cautionary Note on Forward-Looking Statements

This press release contains forward-looking statements about the
Company's strategy, future plans and prospects, including statements
regarding the development of the Company's compounds, including
sotatercept, luspatercept, dalantercept, ACE-083, ACE-2494, the
Company's IntelliTrap™ drug discovery platform, and the Company's
TGF-beta superfamily program generally, the timeline for clinical
development and regulatory approval of the Company's compounds, the
expected timing for the reporting of data from ongoing trials, and the
structure of the Company's planned or pending clinical trials. The words
"anticipate," "believe," "continue," "could," "estimate," "expect,"
"forecast," "goal", "intend," "may," "plan," "potential," "project,"
"should," "strategy," "target," "will," "would," and similar expressions
are intended to identify forward-looking statements, although not all
forward-looking statements contain these identifying words.

Each forward-looking statement is subject to risks and uncertainties
that could cause actual results to differ materially from those
expressed or implied in such statement. Applicable risks and
uncertainties include the risks that the Company’s cash, cash
equivalents and investments will be insufficient to fund operations into
the second half of 2019, that preclinical testing of the Company's
compounds and data from clinical trials may not be predictive of the
results or success of ongoing or later clinical trials, that data may
not be available when the Company expects it to be, that the Company or
its collaboration partner, Celgene, will be unable to successfully
complete the clinical development of the Company's compounds, that the
development of the Company's compounds will take longer or cost more
than planned, that the Company or Celgene may be delayed in initiating
or completing any clinical trials, that the Company's drug discovery
activities may not yield drug candidates for which the Company can
commence clinical trials at the rate at which the Company currently
anticipates or at all, and that the Company's compounds will not receive
regulatory approval or become commercially successful products.

Other risks and uncertainties include those identified under the heading
“Risk Factors” included in the Company’s Annual Report on Form 10-K
which was filed with the Securities and Exchange Commission (SEC) on
March 1, 2017, and other filings that the Company has made and may make
with the SEC in the future. The forward-looking statements contained in
this press release reflect the Company's current views with respect to
future events, and the Company does not undertake and specifically
disclaims any obligation to update any forward-looking statements.